1. Field of the Invention
The present invention relates to an electric motor built-in wheel structure, in which an electric motor is not influenced by wear powders of a brake mechanism and the brake mechanism is not influenced by beat of the electric motor, and which is small and compact.
2. Description of Background Art
One example of a conventional wheel structure for a vehicle is shown in Japanese Unexamined Utility Model No. Sho-49-132546, entitled “Electrically operated small vehicle”.
FIG. 2 of the publication describes a wheel structure with a hub 5 rotatably attached to an axle 6 via a bearing 7, a tire 4 attached to the hub 5, and an electric motor disposed in a wheel by attaching an armature 9 to the axle 6 and attaching a field 8 to the hub 5.
A braking mechanism may be either a drum brake or a disc brake and is usually attached to a wheel. However, when attaching a brake mechanism to the above-described wheel, the brake mechanism is disposed between a sidewall of the hub 5 and the vehicle body side.
In such a structure, the wheel and the brake mechanism are arranged in a direction extending from the axle 6, so that vehicle width increases. Consequently, the structure is not suitable for a motorcycle, for example. Also, in the case where a drum brake is disposed in the wheel adjacent to the armature 9, the width of the wheel increases. Moreover, mechanism wear powders may adhere to the field 8 in the wheel, degrading the performance of the electric motor. In addition, heat generated by the electric motor may degrade the performance of the brake mechanism.